Enye yeenjini zophuhliso lwezoqoqosho kwisiqingatha sesibini senkulungwane yokugqibela yayiyiplastiki. Zincinci, zilula ukuvelisa, zixhathisa, zi-elastic kwaye, ukuba zikhululekile, zicacile, kodwa zinecala le-b, ekubeni zingenakukwazi ukubola, kuba akukho nto ephilayo ekwazi ukuzondla kuzo.
Ukuqina kwazo ixesha elide, ngaphandle kwamathandabuzo, ngomnye wemingeni emikhulu esijongene nayo, kuba ubuncinci beminyaka engamakhulu amane anamashumi amahlanu kufuneka budlule ukuze iipolymers ziqalise inkqubo yokuqhekeka kwinqanaba lemolekyuli.
Kuqikelelwa ukuba ngaphezulu kwe-300 yezigidi zeetoni zeplastiki ziveliswa kwihlabathi jikelele, apho i-90% yazo iphuma kwi-oyile kwaye inxalenye encinci, emalunga ne-15%, iya kufunyanwa kwaye iphinde ifumaneke kwihlabathi jikelele.
Kweso sixa seenkwenkwezi, umyinge weetoni ezizizigidi ezisibhozo ziphela zidada minyaka le kwiilwandlekazi zethu, apho zitshona khona, ziqokelelane kwintlenga okanye ekugqibeleni zidityaniswe kukutya kwabantu.
Uqikelelo lwexesha elifutshane alukho kwaphela, amanye amazwi agunyazisiweyo aqikelela ukuba ngo-2050 ukuveliswa kwenkunkuma yeplastiki kuya kufikelela kwiitoni ezibhiliyoni ezilishumi elinesithathu. Umfanekiso othi, ngaphandle kwamathandabuzo, usinyanzele ukuba sithathe amanyathelo anamandla nangxamisekileyo.
Enkosi ngo-2016 sifumene ubukho bomlingane onokwenzeka kwaye, njengoko kwenzekile amaxesha amaninzi kwimbali yesayensi, i-serendipity idlale indima ebalulekileyo. Kulo nyaka iqela lezazinzulu zaseJapan liphande ngeentsholongwane zebhaktiriya kumzi-mveliso wokurisayikilisha kwisixeko saseSakai, eJapan. Ngeli xesha sihlalutye ibhaktheriya ekhutshwe kwi-polyethylene terephthalate (PET) intsalela ngaphezu kwecandelo (i-ethylene glycol kunye ne-terephthalic acid).
Bothukile, bafumanisa ukuba ibhaktiriya, ebizwa ngokuba yi-Ideonella sakaiensis, iyakwazi ukusebenzisa i-PET njengomthombo oyintloko wekhabhoni. Ngexesha elithile kamva kwakunokwenzeka ukubonisa ukuba i-microorganism ineendlela ezimbini eziphambili ezinokuthi 'ziqwenge' i-PET: i-PETase kunye ne-mono(2-hiroexieethyl) terephthalate hydrolase.
Isisombululo esinethemba
Ukufunyaniswa kwetsheyini ye-metabolic kwenze ukuba kube lula ukuchaza ukuba kutheni i-Ideonella imisele indawo yokuhlala kwisityalo sokuphinda isetyenziswe, kodwa into ekusafuneka ityhilwe yile nto ibiyindlela yokuba ibhaktiriya ivele ukuguqula iplastiki, eyayinelungelo elilodwa lomenzi wechiza. ishumi leminyaka engamashumi amane enkulungwane edlulileyo, kumthombo wayo wokutya.
Ibhaktiriya iyakwazi ukuguqula i-PET ibe yi-poly(3-hydroxybutyrate) - ekwaziwa njenge-PHB - luhlobo lweplastiki enokubola. Isibheno seli bali kukuba i-PET iqikelelwa ukuba iyancipha kwizinga le-0,13mg nge-square centimeter ngosuku, kwiqondo lokushisa le-30ºC, izinga lokuphelisa eliba 'licotha kakhulu'.
Ithamsanqa lancuma kuthi kwakhona ngo-2018 xa abaphandi beYunivesithi yasePostmouth (e-UK) bayila ngempazamo i-enzyme eyandisa i-PETase yebhaktiriya.
Ngeli xesha, izanywe ukuthatha elinye inyathelo ukukhulisa imveliso yayo 'ngokufaka' i-enzayimi eguqukayo kwibhaktiriya ye-extremophile, ekwaziyo ukumelana namaqondo obushushu angaphezu kwe-70ºC, umfanekiso apho i-PET ibonakala kakhulu. Oku 'gqithisela' kunokukhawulezisa inkqubo yokwehlisa umgangatho ukuya kuthi ga kwi-10%.
Zonke ezi zinto zifunyanisiweyo zinokusinika ukuphumla kwaye zivule ifestile yethemba, ekubeni ibhaktiriya 'idla iiplastiki' iya kuba yinxalenye yesisombululo kwingxaki yokusingqongileyo ebangelwa ziiplastiki.
UMnu Jara
U-Pedro Gargantilla yi-internist kwisibhedlele i-El Escorial (Madrid) kunye nombhali weencwadi ezininzi ezidumileyo.
